Are Two Flashes Better than One?

One of the most common questions relating to flash
photography is whether or not your photographs will benefit from using
more than one flash. The answer to that, of course, depends entirely on
a wide variety of factors, ranging from personal preferences to the
type of effect you are attempting to create in your photograph. Below
you will find a breakdown of situations where two flashes might be
preferred over one single flash, and situations where one flash will
typically be more effective.

Using a Single Flash

For the most part, the vast majority of your photographs will not
differ appreciably when using multiple flashes. In terms of photo
quality, the difference between using one flash or two flashes will not
affect your photos to a great degree in most lighting conditions. The
main complaint against using a single flash is that this will create
images that are considered "flat" in comparison to images created
through the use of multiple flashes. While this is true to some degree,
most casual photographers will not notice or will not care about the
difference in quality created by a single flash when compared to
multiple flashes.

The relative benefit, therefore, will generally come from the time
and preparation that you will save by using a single built-in or shoe
mounted flash. For most lighting situations, then, it would be fair to
say that it is generally better from a simplicity standpoint to use a
single flash. There are certain situations, however, where multiple
flashes will be beneficial, and these will be discussed below.

Using Multiple Flashes

In some instances, you will want to create more interesting
composition by adding an additional flash to your artificial lighting
setup. Multiple flashes can be mounted together on your camera through
the hot shoe or can be positioned externally to the camera itself and
triggered remotely through the use of a device known as a flash slave.
By positioning lights at angles other than straight at your subject,
you can illuminate different areas of your composition, such as the
background of your image. This can often create an effect that is more
realistic and closely mimics the effects of natural lighting on a
subject.

One excellent example of a situation where multiple flashes are
often used to create a more realistic and interesting photographic
effect is cave photography. When shooting images in a cave or similar
setting, you have multiple unique conditions to consider. First, the
ambient lighting in the environment will be virtually nonexistent. This
means that all of the lighting effects in your image will be created
through the artificial light triggered by your camera. A single,
straight-on flash will create relatively flat images devoid of shadows,
which will appear unrealistic when compared to photographs
incorporating multiple flashes. Using two flashes can serve to bounce
light off of the roof or sides of a cave to illuminate the cave
features from different angles, which creates a more interesting and
realistic effect.